I have a 2005 f350 crew cab DRW 6.0 with Troqueshift and when I hook my gooseneck up to it, the trailer sits on it and the rearend sinks normally. From a dead stop the rear end feels like a heavy shake and then its totally fine. It only does this when it has a heavy load on it. I took it to the dealer and they put shims between the driveshaft and the frame in order to compensate for the pinion. I was told that it may be the clutch pads in the read of the gear for the transmission. The shims did nothing really but only gave a slight vibration going down the highway.I think I need to have the shims taken out back to the normal setting and from there I am not sure. Anyone have any comments?? Oh by the way the 6.0 rules! It is def. a powerhouse!

Please Help guys! I need anything anyone here can offer.

 

"I took it to the dealer and they put shims between the driveshaft and the frame in order to compensate for the pinion."

To correctly state this- They put wedge shims between the leaf springs and rear differential housing to adjust the pinion yoke angle. This will slightly adjust the drive shaft angle and keep the universal joints in phase. The problem with this is that it normally fixes the condition under tongue weight. But not when empty.

"I was told that it may be the clutch pads in the read of the gear for the transmission."

You've got me absolutely baffled with this statement. If the clutches in the transmission were chattering, it's due for some repair. If they meant the clutch pack in the differential, the It too is due for repair. They might chatter on a turn, but not from an equal traction straight line start.

I've never had a fifth wheel. But is there a load leveling device for these? Can the angle of the hitch be adjusted to distribute the load a bit differently? As for the truck settling with load, If you don't get the vibration when empty, I'd attempt to keep the same ride height/pinion angle when loaded. I would install overload springs or adjustable airbags above the axle housing.

I would be surprised that the mechanics at the dealership didn't check , but did you have them check the universal joints and the carrier bearing for the driveline? Those will also provide vibrations if they're worn out or not greased regularly. You might not notice them if unloaded. But the vibrations would be amplified if those components were worn out.

 

Nice post Steve...I like the question in a different color, makes my old eyes see it easier.

 

Well my truck has only 6,000 miles on it. I dont think this is a joint problem. Oh by the way I went in the back and I watched them put shims between the frame and the bearing where the 2 peice drive shaft comes together. They just put 2 inbetween it in order to lower it. Thats it. Nothing was done to the rear end AT ALL.

 

Oh I forgot.....there is no way to adjust the hitch itself. I am upset b/c my 1999 7.3 f350 crew cab drw pulled it fine no problems and now this new 50 grand truck is supposed to have more payload than the truck I replaced it with. I am getting a feeling from your post that my f350 is not capable of pulling this trailer without shaking on the take off. Is that true? The trailer only weighs 11,000 pounds. I am baffled

 

No, no, Your new truck is quite capable of towing your trailer. But the fix for the shutter that the dealer did was the opposite needed in my mind. Shimming the top mount of the carrier bearing to drop it's center was wrong.

As the truck frame settles, the pinion angle is actually reduced in relation to the angle the drive line is as it comes aft from the carrier bearing. The mechanics actually reduced the angle more at the rear pinion/diff but increased it at the transmission/transfercase. The key is, with a two piece drive line, the carrier bearing is just a place to allow "limited flex, or "more stability" in the middle of what should be considered a once piece drive shaft. The pinion angle at the exit of the transmission/transfercase and the pinion angle at the rear differential should be the same. -In theory. And you never want it completely straight. Then you won't use the needle bearings in the Ujoints. IF they don't roll, eventually the'll crush, become loose inside and the joing itself will break.

The differential is allowed to move up and down with load change and suspension travel. The trasmission position stays static. Another problem is that the rear differential also changes pinion angle as it travels up and down. And.. It changes more angle when torque is applied. The yoke travels up. This all equates to a bit of vibration at certain rpm's. All of it will never go away. But since you can feel it, I'm leaning that there's too much vibration. If we had four link rear suspensions, our vibration days would be over for the most part. But I don't see them in the future for pickup trucks.

That vibration is usually caused by an out of phase condition in the drive line pieces. This is where the roller bearings in the universal joints rotate at a different rate than the ujoints at the other end of the driveline. It creates a harmonic through the tube. That makes it bounce. It'll also wear out the ujoint bearings, pinion bearings and seals. Too much angle difference causes the same, even if they're in phase -such like extremely lifted 4x4 trucks.

In my experience, the only way to combat your situation, If it is truly just pinion angle, is to wedge shim the axle on the leaf springs, and possibly drop the center carrier bearing. But dropping the carrier bearing is normally only done on suspension lifted trucks. Not in your case where essentually you're lowering the bed with load. The only way to change this is to rotate the axle housing on the leaf spring mounts, which will adjust the pinion angle.

That said, this vibration might not be a differential, pinion, or driveline thing. If the shims changed the characteristics of the vibration, then maybe they're on the correct road, but they might be traveling south instead of north.

The 7.3 engine is also a different bugger than the 6.0. The 6.0 does have a different vibration as it starts to pull a load from a stand still. I would also have the dealership do a full four wheel alignment. If there are differential issues an oil analysis on the diff lube should indicate something if it exists. An improperly installed pinion bearing would give you a vibration under load. The metal from that wearing bearing/race would show in the oil test results.

I hope this helps.



You might also want to get a different oppion from a driveline specialist. Just about ever major city has a shop that just builds drivelines. Sometimes a sub business of a transmission shop.

 

GREAT post

 

That it is, and a good thread period

 

I had a company truck (we have bunches of them, so I have seen a lot of stuff in the last few years) that had a very heavy vibration on take off. The truck was a F-550 2wd 6.0 with 4.33 gears and weighed 15,200 lbs. I took it into my favorite dealer and told them the problem, the added shims to the carrier bearing and then took some out and then added some more and then took some of those out and finally told me to come n git it. When I picked it up, all was well, only a very slight shake when taking off even at WOT, but when I got on the interstate I found out that they had "moved" the vibration to 62 MPH. At exactly 62 it would shake enough that the radio lights looked fuzzy, then at 66, it smoothed out. I took it back and they added one more shim and it was smooth enough that I delivered it to my customer and they have never called complaining. Maybe it's just a matter of getting the combination right. Of course a driveline shop could definitely help, but FMC won't foot the bill for that one. Good luck and I hope it all gets smmmmoooooooovvvveedddd out for you...Mat.

 

Oh and all of those shims were "kits" from FMC, not something that the dealer did to make me go away. I see them too often for that to work. I agree, it's odd to lower the carrier bearing to eliminate a problem that only seems to get worse as more weight is added to the rear axle, but it did fix the take-off vibration on our truck.

 

Well let me ask you this Jack....is this hurting my truck with this take off shake? Will it be possible to get it not shaking and not have to buy these air bags or anything like that?

 

"is this hurting my truck with this take off shake?"
If we're talking about pinion/driveline angle that's creating the shake. Yes, it wears things. But not so much that tomorrow your pinion seal is going to start leaking. Any out of balance or vibration wear's components faster than things that work in harmony. I would still rule out differential and alignment problems. If the shims at the carrier bearing did change the shake, then I'd keep working with the driveline angle as the culpret. It's difficult to diagnose since I haven't felt it. That's why I'm attempting to share as much information as possible. At least then when the dealer mechanic farts smoke, you'll know when to ask another question. Unfortunately, most mechanics aren't well versed in this sort of thing. It does bother me that you are having this much shake. Generally this is common with lifted trucks, not one with a stock ride height, then a load. Reducing the angles doesn't normally create vibration. Usually it reduces it. And you say there's no vibration at any speed when not loaded? When loaded, is this a vibration/thump from a stop to about ten mph? Then it fades to nothing?

"Will it be possible to get it not shaking and not have to buy these air bags or anything like that?"
Yes, but these things take a while to find the right combination of shims to get just the right setting. It's mostly trial and error. And, the mechanics you consulted attempted the easy fix. The carrier bearing is held on with two bolts. Loosen a bit, shove in a couple shims, tighten, and viola, he hoped it was fixed. But the wedge shims at the leaf springs/axle housing take a bit more work. It's not impossible though. Since it's not a truck out of service type of thing, I'd have a good talk with the service manager and arange some trial and error fits. You might even hook up the trailer and give him a test ride. You could, before you go to that trouble, look up a friend with a similar trailer and hook it up. You could.. Have a situation where the trailer is the problem, and the new truck is just transfering a vibration that you didn't feel in the old truck.

Yes, there are some shim kits available from FMC that they can use. -Not that there's any sort of service bulletin on this type of thing. They may need to order the kits. If you had 300lbs less tongue weight, you might not even feel this. And in most cases, that would be true.

Something else: I mentioned driveline phasing somewhere above. This is different than the angles. There is a possibility that the slip yoke at middle of the driveline was assembled incorrectly. That done, will create a nasty vibration at intervals of RPM. And be pronounced when starting out.

There's possibility that the driveline itself has lost one of it's balance weights. But you normally don't feel that out of balance condition until traveling down the road.

Here's a pretty good web site that explains in more detail than I have. In this link the author discusses how the vibration created at the driven Ujoint cancels out the vibration of the driving Ujoint. This can only occur when the two pinion/yoke angles are the same at both ends of the drive line.
http://www.4crawler.com/4x4/CheapTricks/Driveline-101.shtml#Double-Cardan-Measurements

 

I have a 2005 dually that never squats much when loaded, but i hear such a popping noise when loaded now when i am empty the truck pops i was told i needed three shimmy kits. THREE???????

 

Hey Jack.....actually all I am having a problem with is that the truck just shakes from a dead stop just to get it wound up. Thats it. It lasts about one second. From 3mph on up everything is totally fine.....no vibrations or anything at all. Shifts great no vibrations at all going down the highway running 90 mph =) but the only issue is that dead stop take off there is a bad shake. It feels like its in the rear and the rear is trying to shake apart. for a second or two. It feels like the truck shakes bad to turn up like a turbo but only in the rear. Once its going and takes off everything is totally fine. What do you think? Does this help you understand better?

 

Do you have a limited slip rear differential?